Oldest person = Dad

And go first with No. 2. The oldest person and the withness were not of the same sex so from that,

Witness = Female (Mum or Daughter) because Dad is the oldest and he is a man.

I came to this conclusion:

Let's check,

1) The witness and the one who helped the Murderer were not of the same sex.

Answer:

2) The oldest person and the witness were not of the same sex.

Answer:

3) The youngest person and the victim were not of the same sex.

Answer

4) The one who helped the Murderer was older than the victim.

Answer:

5) The father was the oldest member of the family.

This is my first clue and direct me to others.

6) The Murderer was not the youngest member of the family.

Answer:

And the last one..

Ok, my brain bleeds. But here's my answer after years of thinking lol.

1. I thought at first that this is a stupid, unreasonable question. But no.
   My answer is Stan's birthday is December 31 and let's say 2017. Phil asked him in Jan. 1, 2018 so 2 days before (December 30, 2017), he was 32. His birthday the next day December 31, 2017 he becomes 33. This year 2018 on December 31 he will be 34 and next year 2019 he will be 35.

2. They said, "Hello, Father!" Their priest you know. We call our priest, Father.

3. Haha, don't know how to do this one. But let me try. We both have 10 apples if she gave it to me, mine will be 20 and hers is none. So we have 10 apples, she not need to gave me anyything, just eat it all and so she will leave with nothing and I got 10 still. So I can have 10 more apples than her!

Please check his contest in this link.

THANK YOU SO MUCH!